An urtrasonic inspection and imaging instrument as one of ultrasonic measurement instruments is capable of displaying the interior of an object under examination in the form of a B- and a C- scope image. An imaging instrument of this sort, in order to obtain a clear image, necessitates such as setting and selection of various measurement conditions including acoustic characteristic of its probe, sound velocity in a medium and an object under examination at their instant temperature and the like, setting a gate in the object under examination at a desired depth according to the selected measurement condition and further, focusing operation setting the focus for the probe.
Conventionally, for the gate setting and the focusing operation, a reflection waveform (an A scope image) from the object under examination was observed by using an oscilloscope or the like, a desired measurement depth, detection gate width and the like were set according to the observed waveform as well as an operation of moving up and down (positioning in Z direction) of a focusing type ultrasonic probe (hereinafter simply called as probe) with respect to the object under examination was performed so as to focus the probe at a desired measurement depth and further to maximize a target reflection echo.
However, in case of an inspection of defects existing inside a measurement specimen such as cracks, voids and foreign matters, the shapes of the defects are indefinite, for this reason the intensities of defect echos from these defects vary and could not be detected in a uniform manner. Further, the location and depth of defects are frequently indeterminable in certain types of objects under examination. For this reason, a measurement is performed by provisionally selecting setting values and setting measurement conditions.
Accordingly, for the purpose of selecting an optimum measurement condition for a certain object under examination, such as proble height, probe gain and gate position which provide an optimum image are determined while observing images obtained by probe scanning. In particular, in an arrangement in which such as the probe height, probe gain and gate position are set via a computer control there are many setting numbers for the measurement conditions or for their parameters and the programs are started on every condition and setting such that it takes great many time for the operation. Moreover, there is no guarantee that the measurement condition with regard to the above items is an optimum one which is resulted from the several time measurements.
This is because that such as the probe gain, gate position, focusing position and defect condition are affected each other and even when one of the parameters is modified while monitoring an image under a certain measurement condition the condition of the other parameters vary such that a desired measurement image can not be frequently obtained unless all of the parameters are reset. In such instance one particular parameter is noted and only the value of the noted parameter is varied so as to select a measurement condition while fixing the values of the other parameters, however since there are so many parameters that it takes long time for selecting an optimum measurement condition. Moreover, when the noting is changed[to another parameter and the relationship between the previously noted parameter of which value are already determined and the presently noted parameter is at the same time varied, the setting operations are frequently messed up.
Because of the above circumstances, a setting of an optimum measurement condition for a measurement specimen is comparatively difficult and time comsuming except for an experienced person and an expert who have experiences in the ultrasonic measurement and well know the relation between measurement images and corresponding defects.
An object of the present invention is to resolve such conventional problems and to provide an ultrasonic inspection and imaging instrumrnt which permits even for a person inexperienced in an ultrasonic measurement to easily set an optimum or close to optimum proper measurement condition.